1. Field of the Invention
The present invention generally relates to a technology for producing a liquid crystal display device.
2. Description of the Background Art
There are a TN (Twisted Nematic) system, a VA (Vertical Alignment) system or the like, for the liquid crystal display devices, and a PVA (Patterned Vertical Alignment) system having a wider view angle, a higher contrast, and so forth have recently attracted attention.
The PVA system liquid crystal display device possesses a color filter having a colored resin layer and a transparent electrode (counter electrode) laminated on a transparent substrate and a pixel substrate on which a plurality of pixel electrodes are disposed on a substrate. The transparent electrode of the color filter is patterned, and an opened pattern (opening) is formed.
The color filter and the pixel substrate are bonded oppositely across a liquid crystal. The openings of the transparent electrode are located immediately above the respective pixel electrodes. When a voltage is applied between a selected pixel electrode and the transparent electrode, the electric field between the pixel electrode and the transparent electrode becomes oblique to a surface of the pixel electrode, so that major axes of molecules of the liquid crystal are obliquely inclined relative to the surface of the pixel electrode, and the view angle becomes wide. In this connection, an example of the PVA system liquid crystal display device is described in Patent Document 1 listed below.
In general, the transparent electrode is patterned by dissolving predetermined portions of the transparent electrode into an etching liquid, with a SiO2 thin film disposed between the resin layer and the transparent electrode. Since the SiO2 thin film has high transparency and is not dissolved into the etching liquid for etching the transparent electrode, it functions as an etching stopper.
However, since the SiO2 film largely differs in linear expansion coefficient from the transparent electrode (such as, for example, ITO), there was a problem that the transparent electrode was likely to be exfoliated from the SiO2 film.
In forming a SiO2 film, there is available a sputtering method in which a SiO2 target is sputtered and a reactive sputtering method for sputtering a Si target while oxygen is being introduced.
However, when the SiO2 target is used, an RF (radio frequency) power source is employed because the discharging of electricity is not stabilized in such cases as when a DC (direct current) power source or an AC (alternate current) power source is used. Usually, when the transparent electroconductive film (ITO) is subsequently formed by sputtering, the AC or DC power source is used. However, since they differ from the RF power source in the manner in which they are installed, it has been necessary to separate chambers for forming the SiO2 film and for forming the transparent electroconductive film (ITO).
Also, when the reactive sputtering is used to sputter an Si target, a large amount of oxygen is introduced, so that the chamber for introducing oxygen has to be separated from the chamber for forming the ITO film by sputtering. For this reason, it was difficult to form a SiO2 film and a transparent electrode film (ITO) in the same chamber, thereby resulting in the production of apparatuses that are large.
Further, in using the reactive sputtering for the formation of the SiO2 film, there have been the problems due to the occurrence of arcing, and of low film forming speed. Moreover, when the RF power source is used, the cost of the apparatus tend to increase due to the added costs of the power source and treatment for surface waves.
It is desirable that the film as an etching stopper and the transparent electroconductive film can be formed in one and the same chamber, so as to reduce the size of the entire apparatus and decreases the manufacturing cost thereof.
See Japanese Patent Documents JP-A 2003-287618, JP-A 2001-174838, and JP-A 7-318713.